29 



inches, the ribbon at its widest part being about half an inch. 

 The orifices of the marginal zooecia are nearly circular, with a 

 prominent denticle ; in the older the peristome is much produced 

 as in the var. himucronata. The avicularia, when present, are 

 usually large, by one side of the mouth, with the mandible- 

 pointed downwards. There are numerous ooecia with large per- 

 forations. 



MucROXELLA, Hincks. 

 M. EUerii, McG. St. Vincent's Gulf. 

 M. jKqnllifera, McG. 



Adeoxella, Busk. 

 A. platalea, Busk. St. Vincent Gulf. 



FAMILY CELLEPORID^. 

 Lekythopora, JIcG. 

 L. hystrix, McG. 



Cellepora, Fabricius. 

 C. HrcUa, McG. 

 C. cidaris, McG. 

 C. verrucosa, McG. 



SCHISMOPORA, McG. 

 S. costata, McG. 



FAMILY RETEPORID^. 

 Retepora, Imperato. 



R. phodnicea, Busk. Kangaroo Island. 



R. monilifera, McG., var. simiata. 



R. monilifera, form arcuata. A specimen occurs differing 

 especially in the ooecium which it is desirable to distinguish. The 

 zoarium, about three and a half inches in longest diameter, forms 

 a tubular and calyculate mass. The fenestra? are oval, narrower 

 than the trabecuhie. The peristome of the zooecia is produced 

 with a loop-shaped notch, on one side of which is a rounded avic- 

 ularium. There are also frequent elliptical avicularia on the 

 front of the zoa?cia, and horizontal avicularia on the inner edge of 

 the lower part of the fenestra:". The ooecia have an arched or 

 angled beaded line or stigma without vertical extension. The 

 posterior surface is faintly vitricate and granular, with small 

 elliptical avicularia, especially towards the margin of the 

 fenestra?. 



I am not satisfied that the forms I have described as munita 

 and mnhonata should not rather be considered as species, in 

 which case this would take similar rank. 



